9.2.1 How Automatic Backups Work in a Calendar Server
6.3 System

The Calendar Server system records each transaction for the calendar
database (additions, modifications or deletions to calendars and their properties)
in a transaction log file. At some predetermined interval, the log file is
closed for writing and another is created. The system then applies the transactions
from the oldest closed transaction log to the live calendar databases as time
permits. When all the transactions in the log have been applied to the database,
the log is marked as “already applied”.

When hot backups are configured, a snapshot of the live databases is
taken every 24 hours. The already applied logs are then applied to the hot
backup copy of the databases. The hot backup databases are as current as the
number of transactions still waiting to be applied.

9.2.2 How csstored Works for Backups in a Calendar Server
6.3 System

One of the Calendar Server services launched at startup is csstored. When configured, this service performs automatic backups (either
hot backups or archival backups, or both) of your calendar databases.

You can configure csstored for automatic backups
when you run the configuration program, csconfigurator.sh.
If you choose one or both of the automatic backups at that time, no further
configuration steps are necessary.

If csstored is disabled, none of the other daemons
that access the database will work. The csstored daemon
performs other necessary tasks for the databases. Therefore, the daemon should
not be disabled.

Note –

When automatic backups are disabled, the circular logging ics.conf parameter, caldb.berkeley.circularlogging,
should be set to "yes". This enables purging of old database
transaction logs, which conserves disk space.

9.2.3 How Circular Backups Work in a Calendar Server 6.3
System

With automatic backups enabled, csstored automatically
manages the number of backup copies retained in your backup database files
using a circular backup system.

The csstored process stores backups in your backup
database directory until either the maximum number of backup copies have accumulated,
or the maximum disk space allowed has been reached. At that point, it purges
backup copies (oldest first) until it reaches the minimum number of copies
to retain and it is under the disk space threshold.

There are a cluster of ics.conf parameters that
control circular backups. These parameters have default values, and do not
require further customization. If you wish to tune how backups work in your
system, see 21.7 Tuning Automatic Backups.

9.2.4 High Level Steps for Enabling Automatic Backups

If you did not configure automatic backups when you ran the configuration
file, you can set them up later. This section contains a list of high-level
steps necessary for enabling automatic backups for the Calendar Server 6.3
system after the configuration program has already run.